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I used to ride almost only sand dunes so I am coming off a 450.

Moving to a 250 now that I am riding single track more and just looking for a more agile bike.

 

Yes the 2015 is powerful for a 250, but what if I want MORE out of it while still keeping the handling characteristics.

 

Please give me some suggestions for power modifications, best bang for the buck!

 

The bike will be in everything ranging from tight single track to open desert to MX track.

Riding elevation ranges from 5000 to 8000 ft if that affects any decision when it comes to engine modifications.

 

Here's a picture before the bike break in just to excite some people.

20150430_151951.jpeg

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To many options to list..

Based on the OP question a big bore kit, as mentioned may be a good option.

Ride it stock for a few rides, adjust gearing as needed.

Bang for the buck... Honestly you will gain more from proper chassis setup than anything else.

YES Big bore. head work, cams will add HP and torque but its a waste if you can't hook up..

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To many options to list..

Based on the OP question a big bore kit, as mentioned may be a good option.

Ride it stock for a few rides, adjust gearing as needed.

Bang for the buck... Honestly you will gain more from proper chassis setup than anything else.

YES Big bore. head work, cams will add HP and torque but its a waste if you can't hook up..

You've offered nothing to the discussion. He asked about power mods, not setup help. Your comments assume his ignorance of setup and its effects on performance. He, like me, is likely a bit older and heavier than your typical 250f rider and he just wants a bit more balls to the lighter, more nimble 250f...as compared to the 450s. 

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I used to ride almost only sand dunes so I am coming off a 450.

Moving to a 250 now that I am riding single track more and just looking for a more agile bike.

 

Yes the 2015 is powerful for a 250, but what if I want MORE out of it while still keeping the handling characteristics.

 

Please give me some suggestions for power modifications, best bang for the buck!

 

The bike will be in everything ranging from tight single track to open desert to MX track.

Riding elevation ranges from 5000 to 8000 ft if that affects any decision when it comes to engine modifications.

 

Here's a picture before the bike break in just to excite some people.

I am sorry if my first post wasn't helpful. I'll try harder this time.

First thing I tried was the GYTR tuner, yes it is worth the money just for the monitor function alone. Many maps available or make your own.

The 14+ responds well to many mods, I jumped in head first with head porting, valve mods, cyl and head mods (allows the use of the cheap OE piston as opposed to the spendy GYTR or other hicomp pistons) This was done at the 7 hour mark. I would have had the cams done, but chose to wait.

Performance was better bottom to top with the most noticable gains from upper mid on up.

FMF Ti slip on installed just prior with no noted gains other than better sound and the needed sparky insert. (RCT does not come with the S/A insert)

FMF Ti headpipe kit installed next.. much lighter,, performance gains.. much lighter and looks awesome after some heat cycles.

At 38 hours I installed the No Toil superflow kit as well as the modded cams from the same tuner that did the previous engine mods.

Again, engine performance was boosted everywhere, again with major boost from upper mid to rev limiter.

As I stated previously, options are unlimited.

My reason for pointing out chassis setup are a result of the engine mods. Traction is NOT an issue with the stock engine, with mods it can be and is

an issue for me. I am 46, ride single track, open desert, MX and dunes. I love 450's and 250 2 strokes but they wear me out..

Aside from rear wheel traction issues front end feel and traction have been consistant and awesome.

I am running an MX32 front and X30 rear (120-80-19 on a 2.15 wheel) with 13-49 gearing at this time

Best dollar parts..

GYTR tuner

NO Toil superflow kit.

Engine mods...

Edited by MJP68
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You've offered nothing to the discussion. He asked about power mods, not setup help. Your comments assume his ignorance of setup and its effects on performance. He, like me, is likely a bit older and heavier than your typical 250f rider and he just wants a bit more balls to the lighter, more nimble 250f...as compared to the 450s.

You mentioned mods you haven't even installed yet.. have you even ridden the bike stock?

How is that more constructive?

46 is conservative based on the parts you say you might install someday..

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You mentioned mods you haven't even installed yet.. have you even ridden the bike stock?

How is that more constructive?

46 is conservative based on the parts you say you might install someday..

My comment about power mods was based on my research and planning for my build. No, I have not started building it yet but I will this month. I am an ER physician and we are short staffed so I have had to work more shifts than normal and I have had no time to ride...or work on the bike. 

The parts are all sitting on the table in the garage...trust me, it kills me to walk past it every day on the way out the door to work. 

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like others have posted, a BB kit is the biggest bang for the buck.  mate it with cams to put the power where you want and it will be even better.  the thing about the BB companies is that some spend more effort into designing them than others.  the company you purchase it from should be asking you what your riding conditions are, how your ride, and what you hope to get out of it.  if they just sell you their standard kit with the sales pitch that it will work great for you without knowing anything about you then I would move on.  If you go with a BB kit consider the type of material (iron or plated), number of rings, weight of pin, and if the pin is coated or not.  they all have an effect on the performance of your motor and longevity.  if you have the time and money you could also have the crank balanced to your new piston if the company offers that type of work (assuming they have a machine shop) sometimes they can do more to tailor the kit or even holistic engine mods that will construct the engine you are looking for.  

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2014/15 YZ250F not a very good dune bike IMHO, esp compared to a 450. Best bang for your buck is a 250 2-stroke ... just forget about power mods to your F. You will barely tell the difference in the dunes probably grenade it.

 

99% of all other terrain, YZ250F has great power ... just too linear and not enough ponies in the dunes. Its never going to be a 450 or even a stock 250 2t when it comes to dunes.

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Take your $2000 in hop-up budget and buy a $1500 ~2000ish YZ250 2-stroke. Mix in some av-gas with your pre-pimx, paddle, flag and you'll STOMP on a that shiny new bike.

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Take your $2000 in hop-up budget and buy a $1500 ~2000ish YZ250 2-stroke. Mix in some av-gas with your pre-pimx, paddle, flag and you'll STOMP on a that shiny new bike.

Correct answer!  Save the 250F for the tight stuff.

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I have GYTR ported head with Crower cams, 276cc big bore, Vortex ignition, FMF exhaust system, Hinson clutch etc...looking to get around 46hp. Expensive, but you only live once. 

I would definitely be interested in what rear wheel #'s you get out of it when its all done up and tuned. What fuel are you planning on running with that set up?

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There are a lot of useful information here, but I have some questions.

While some people recommended switching to YZ450F, I don’t think I’m quite yet ready as I’m riding only for 3 years now (I did won amateur championship last year, but still a lot to learn although competing against 450s). The only other option is improving my YZ250F 2015.

So help me with my decision. One thing is for sure, I’ll be installing big bore kit from Athena (270 or 290 if available, will know later today), port the head and re-valve my suspension. Don’t think there is a need for an aftermarket exhaust as many people said the stock is quite good. Instead, I would rather buy GET Evo Basic ECU.

The things that I’m wondering are:
-Do I install hotcams stage 1 or 2 cams? They cost around 400$, and what are the differences compared to much more expensive GYTR? I don't over-rev my bike, and like good mid-range power

-My bike has 60 hours, and with the new bb kit, I'll replace my crank. Which one? Thinking about either CW or Hot Rods. Or I'm good with OEM?

-The bearings in the engine can stay for 50 more hours? And the crankshaft? Considering there will be more power and load on those two..

-what about clutch? It would be great to have rekluse or hinson, but they are quite expensive. What are your thoughts about them? To go with it or I could be just fome with the stock. Not a big clutch abuser

If I had money, I would purchase everything I can for the engine, but I don't have so keep that in mind as well :)

Edited by Quake

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Would be interested to hear how this kit feels at track. How much does it has engine braking and does it rev free?

I'm still tinkering with mine. It's going to the tuner shortly. I'm waiting for my Genius TB to get here. I will know later this month.

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And the tuner is thinking closer to 50hp!

And the tuner is thinking closer to 50hp!

That is what I would expect as well considering 48+ can be achieved with the stock bore size.

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